Just two months ago, New Mexico was dry. Nearly the entire state was classified as experiencing extreme or exceptional drought. Well what a difference September makes. Now most of New Mexico has received above-average rainfall, even record rainfall in some places. It's a big relief, but as any climate scientist will tell you: One month does not end a drought. In fact, this drought and others before it have permanently changed the land and the way it's used. NPR's Ted Robbins reports.

TED ROBBINS, BYLINE: It's drizzling near Deming, New Mexico, as Steve Willmeth stops to show me part of his ranch.

STEVE WILLMETH: We're going to get mud on you.

ROBBINS: We pull over on a dirt road next to a pasture of wild grasses. Willmeth is dressed in jeans, a checked shirt and a white cowboy hat. His family's been ranching for generations, but he bought this grazing allotment 10 years ago. Since then, he says he spent hundreds of thousands of dollars installing pipes to get water from wells to cattle in dry times. He also rests pastures to let the grass grow. There are no cattle on the land right next to us. Still, if these rains hadn't interrupted the 10-year drought, he'd have faced a tough decision.

WILLMETH: That decision would have been to liquidate more cattle. And if it hadn't rained at all, then the decision would've been made to liquidate everything.

ROBBINS: The biggest change on Willmeth's land and all over the arid Southwest is that ranchers routinely own fewer cattle than they used to. Now, most realize the land just can't handle more.

WILLMETH: We are in a land of drought and that is just the fact of life we face. And we have to adjust to the conditions of it.

ROBBINS: For more than a century, southwestern New Mexico was habitually overgrazed. The Bureau of Land Management, which administers most of the land, still allows twice as much cattle as the 600 ranchers in the area now own. The effects of that former overgrazing have been gradual yet stark.

KRIS HAVSTAD: We're on a site right here that has just slowly changed over the last hundred years.

ROBBINS: From the top of a steel tower, Kris Havstad looks over the Jornada Experimental Range, managed by New Mexico State University, northwest of Las Cruces. The Jornada is an area of grassland, mountains and desert the size of New York City. It's used to observe the effects of ranching practices and of climate change. There's more than a century of data now. Havstad, the lead scientist here, says much of the area used to be grassland. Then came the drought in the 1930s and again in the 1950s, and the overgrazed land changed.

HAVSTAD: Less ground covered, more exposed surfaces.

ROBBINS: Much of the grassland has changed, more or less permanently, to desert.

HAVSTAD: And the impact of that in terms of the environment is those surfaces contribute tremendous amounts of dust to the atmosphere.

ROBBINS: Research shows that dust in the atmosphere can in turn further cut the chance of rain. And that's not just a problem here. That dust can spread in the atmosphere all over the continent. Not much can be done to reverse what's already happened to the land here. But the change to desert is being slowed, if not stopped. The Jornada has gone from 20,000 down to 200 head of cattle.

As we bounce over the dirt roads through patches of desert and grassland, Kris Havstad tells me that's really made a difference over the last decade.

HAVSTAD: Think about the widespread Dust Bowl of the '30s. We had a drought now in the last few years that's similar. But it came nowhere close to the kinds of devastation of the '30s.

ROBBINS: Ranchers in southwest New Mexico who haven't adapted to drought are out of business. Those who are left are better land managers. They have to be. Otherwise, they'll have no grassland left to graze. Ted Robbins, NPR News.

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